An acceptorless dehydrogenation of heterocycles catalyzed by frustrated Lewis pairs (FLPs) was developed. Oxidation with concomitant liberation of molecular hydrogen proceeded in high to excellent ...yields for N‐protected indolines as well as four other substrate classes. The mechanism of this unprecedented FLP‐catalyzed reaction was investigated by mechanistic studies, characterization of reaction intermediates by NMR spectroscopy and X‐ray crystal analysis, and by quantum‐mechanical calculations. Hydrogen liberation from the ammonium hydridoborate intermediate is the rate‐determining step of the oxidation. The addition of a weaker Lewis acid as a hydride shuttle increased the reaction rate by a factor of 2.28 through a second catalytic cycle.
The acceptorless dehydrogenation of N‐protected indolines and other heterocycles is catalyzed by frustrated Lewis pairs. Mechanistic as well as quantum‐mechanical studies revealed the liberation of molecular hydrogen to be the rate‐determining step. The addition of a weaker Lewis acid as a hydride shuttle increased the reaction rate by a factor of 2.28.
At the beginning of the 20th century, early processes of secularization – especially in working-class families living in large cities – and inadequate teaching methods led to a crisis of Catholic ...religious education. Teachers and professors highlighted that it was becoming more and more difficult for religious education to reach students and to ensure that they become devoted members of the Church. In this situation, a catechetical movement was established, which was mainly situated in Munich and Vienna, where teachers, catechists, and academics discussed reforms of the commonly used teaching methods in religious education. Conferences and the foundation of journals followed. It is at least from this point that the process of modernization in the field of religious education in the German-speaking context begins. This modernization gained traction after the Second Vatican Council and was also promoted by the phenomenon of secularization and pluralization after the 1960s. Against this background, the essay will address the following questions: What led to the modernization of religious education that began around 1900? What role was played by the new openness of catechists and theologians for education science and the (religious) pluralization of society? To answer this question, the article will focus on developments between 1900 and the 1920s, during the 1970s, and the more or less topical discussion about the concept of ‘theology of children’ since the late 1990s. This study will also ask whether this development can be described as the discovery of the child in theology and religious education. Finally, this paper asks what consequences this development has for a denominational religious education in state schools today and in the future.
We show that DNA-based self-assembly can serve as a general and flexible tool to construct artificial flagella of several micrometers in length and only tens of nanometers in diameter. By attaching ...the DNA flagella to biocompatible magnetic microparticles, we provide a proof of concept demonstration of hybrid structures that, when rotated in an external magnetic field, propel by means of a flagellar bundle, similar to self-propelling peritrichous bacteria. Our theoretical analysis predicts that flagellar bundles that possess a length-dependent bending stiffness should exhibit a superior swimming speed compared to swimmers with a single appendage. The DNA self-assembly method permits the realization of these improved flagellar bundles in good agreement with our quantitative model. DNA flagella with well-controlled shape could fundamentally increase the functionality of fully biocompatible nanorobots and extend the scope and complexity of active materials.
Our conscious experience of the world seems to go in lockstep with our attentional focus: We tend to see, hear, taste, and feel what we attend to, and vice versa. This tight coupling between ...attention and consciousness has given rise to the idea that these two phenomena are indivisible. In the late 1950s, the honoree of this special issue, Charles Eriksen, was among a small group of early pioneers that sought to investigate whether a transient increase in overall level of attention (alertness) in response to a noxious stimulus can be decoupled from conscious perception using experimental techniques. Recent years saw a similar debate regarding whether attention and consciousness are two dissociable processes. Initial evidence that attention and consciousness are two separate processes primarily rested on behavioral data. However, the past couple of years witnessed an explosion of studies aimed at testing this conjecture using neuroscientific techniques. Here we provide an overview of these and related empirical studies on the distinction between the neuronal correlates of attention and consciousness, and detail how advancements in theory and technology can bring about a more detailed understanding of the two. We argue that the most promising approach will combine ever-evolving neurophysiological and interventionist tools with quantitative, empirically testable theories of consciousness that are grounded in a mathematically formalized understanding of phenomenology.
Identifying risk factors of depression can provide a better understanding of the disorder in older people. However, to minimize bias due to the influence of confounders and to detect reverse ...influence, a focus on longitudinal studies using multivariate analysis is required.
A systematic literature search was conducted by searching the databases MEDLINE, Cochrane, PsycINFO and Web of Science for all relevant articles published from January 2000 to the end of March 2020. The following inclusion criteria were used: prospective design, nationally or regionally representative sample, published in English or German, analyzed risk factors for depression of individuals 65+ identified by multivariate analysis, and provided validity of diagnostic instrument. All results of multivariate analysis were reported and summarized.
Thirty articles were identified. Heterogeneous results were found for education, female gender, self-rated health, cognitive impairment and older age, although significant in several studies. Findings hinted at a protective quality of physical activity. In terms of physical health, chronic disease and difficulty initiating sleep homogeneously increased risk of depression. Mobility impairment resulted as a risk factor in three studies. IADL impairment and vision impairment were mostly identified as significant risk factors. Alcohol consumption and smoking behavior yielded heterogenous results. Psychosocial factors were assessed similarly in multiple studies and yielded heterogenous results.
Research was limited to articles published in English or German. Length of follow up was not considered for the presentation of results. Adjustments for and inclusion of different variables in the studies may distort results.
Our findings demonstrate the necessity of refined, more comparable assessment tools for evaluating potential risk factors.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The human malaria parasite Plasmodium falciparum relies on lipids to survive; this makes its lipid metabolism an attractive drug target. The lipid phosphatidylserine (PS) is usually confined to the ...inner leaflet of the red blood cell membrane (RBC) bilayer; however, some studies suggest that infection with the intracellular parasite results in the presence of this lipid in the RBC membrane outer leaflet, where it could act as a recognition signal to phagocytes. Here, we used fluorescent lipid analogues and probes to investigate the enzymatic reactions responsible for maintaining asymmetry between membrane leaflets, and found that in parasitised RBCs the maintenance of membrane asymmetry was partly disrupted, and PS was increased in the outer leaflet. We examined the underlying causes for the differences between uninfected and infected RBCs using fluorescent dyes and probes, and found that calcium levels increased in the infected RBC cytoplasm, whereas membrane cholesterol was depleted from the erythrocyte plasma membrane. We explored the resulting effect of PS exposure on enhanced phagocytosis by monocytes, and show that infected RBCs must expend energy to limit phagocyte recognition, and provide experimental evidence that PS exposure contributes to phagocytic recognition of P. falciparum-infected RBCs. Together, these findings underscore the pivotal role for PS exposure on the surface of Plasmodium falciparum-infected erythrocytes for in vivo interactions with the host immune system, and provide a rationale for targeted antimalarial drug design.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Lipid droplets (LDs) are organelles central to lipid and energy homeostasis across all eukaryotes. In the malaria-causing parasite Plasmodium falciparum the roles of LDs in lipid acquisition from its ...host cells and their metabolism are poorly understood, despite the high demand for lipids in parasite membrane synthesis. We systematically characterised LD size, composition and dynamics across the disease-causing blood infection. Applying split fluorescence emission analysis and 3D Focused Ion Beam-Scanning Electron Microscopy, we observed a decrease in LD size in late schizont stages. LD contraction likely signifies a switch from lipid accumulation to lipid utilisation in preparation for parasite egress from host red blood cells. We demonstrate connections between LDs and several parasite organelles, pointing to potential functional interactions. Chemical inhibition of triacylglyerol (TAG) synthesis or break-down revealed essential LD functions for schizogony and in counteracting lipid toxicity. The dynamics of lipid synthesis, storage and utilisation in P. falciparum LDs might provide a target for new anti-malarial intervention strategies.
Plasmodium falciparum Maier, Alexander G.; Matuschewski, Kai; Zhang, Meng ...
Trends in parasitology,
June 2019, 2019-06-00, 20190601, Letnik:
35, Številka:
6
Journal Article
Recenzirano
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Plasmodium falciparum is the etiological agent of malaria tropica, the leading cause of death due to a vector-borne infectious disease, claiming 0.5 million lives every year. The ...single-cell eukaryote undergoes a complex life cycle and is an obligate intracellular parasite of hepatocytes (clinically silent) and erythrocytes (disease causing). An infection can progress to a wide range of pathologies, including severe anemia and cerebral malaria, which can lead to death. P. falciparum repeatedly replicates over the course of 48h inside erythrocytes, resulting in exponential growth and rapid disease progression. As the single most important infectious disease afflicting children, no other pathogen has exerted a higher selection pressure on the human genome. Over 20 polymorphisms, including the sickle-cell trait, have been selected in human populations, despite severe fitness costs, since they offer protection against fatal P. falciparum infections. No effective vaccine exists, but several curative treatments are available.
The molecular arms race between humans and Plasmodium falciparum in Africa resulted in selection of sickle-cell disease, which, on balance, protects heterozygote carriers against severe malaria. Band ...et al. discovered that parasites counter-adapt and can overcome disease resistance by identifying parasite genome signatures, termed P. falciparum sickle-associated (Pfsa) variants.
"Considered one of the major fields of photonics of the beginning 21st century, plasmonics offers the potential to confine and guide light below the diffraction limit and promises a new generation of ...highly miniaturized photonic devices. Offering both a comprehensive introduction to the field and an extensive overview of the current state of the art,""Plasmonics Fundamentals and Applications""should be of great value to the newcomer and to the experienced researcher.The first part of the book describes the fundamentals of this research area, starting with a review of Maxwell s equations in a form suited to the description of metals. Subsequent chapters introduce the two major ingredients of plasmonics, surface plasmon polaritons at metallic interfaces and localized plasmons in nanostructures. The mathematics of their description, excitation and imaging of the modes are discussed. This part closes with a presentation of electromagnetic surface waves at lower frequencies in the THz and microwave regime, comprising both spoof or designer plasmons and surface phonon polaritons.Building on the fundamentals, the second part discusses some of the most prominent applications of plasmons: Plasmon waveguides, extraordinary transmission through aperturearrays, sensing and surface enhanced Raman scattering, spectroscopy as well as metamaterials. Exemplary studies in each of these fields taken from the original literature are presented."
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